This time, I needed the humidity next to the temperature. I then decided to use a dht11 (you can get it starting at 1.50€ on ebay). Total cost is below 4€. Here below the wiring. Here rf433_sendOOK_at85_dht11 the arduino sketch (rename the txt file to ino). Here some pictures.
Vera et RFXtrx, un couple parfait. Reverse Engineer Wireless Temperature / Humidity / Rain Sensors — Part 1. In this and the next two three blog posts (Part 2, Part 3, and Part 4), I will describe how I reverse engineered a few off-the-shelf wireless temperature, humidity, and rain sensors, and used an Arduino (Update: RPi is also supported now!)

To listen to and decode the sensor data. This has been a really fun journey and I will document the process as thoroughly as I can. Because there are lots of details, I don’t want to jam everything into a single post, so I have split the whole story into three posts. The Arduino and RPi programs are provided at the end of each post. Introduction The first question to ask is always: why am I doing this? Here are the three sensors that I gathered and will use as examples in the following.
Building a Wireless Sensor Network in Your Home. This tutorial will teach you how to create a network of cost effective, wireless sensor modules.

Many of the ready-made wireless modules can be too expensive for use in multiple sensor units. While Wi-Fi and Zigbee modules are popular and easy to use, their cost can make their use in an array of sensors impractical. There are, however, low cost RF modules without all of the expensive features that will work just fine these purposes. The Arduino platform can use low end radio modules to communicate easily and reliably. Once the hardware is assembled, you will leverage the Raspberry Pi platform to post the data to Xively's Internet of Things service where you can track the values over time and trigger on threshold conditions.

This project will include three parts, two transmitter units and one receiver unit. There is a wide range of Arduino compatible boards that can be used for this project. The transmitters themselves are relatively simple circuits. A note about RF use.
[Tuto diy] Fabriquer sonde radio Oregon a 5€ pour les nuls - Forum Domoticz en français. /*Copyright (c) 2007, Jim Studt (original old version - many contributors since) The latest version of this library may be found at: OneWire has been maintained by Paul Stoffregen (paul@pjrc.com) sinceJanuary 2010.